The proposal relates to medicine, and particularly to ophthalmology, and it may be used for measuring intraocular pressure (IOP) through the eyelid both in the cornea region, and in the sclerotic region of an eye by means of express method during mass examination of population on glaucoma, during checking of the correctness of its treatment and during individual control of intraocular pressure without eye anesthetization.
A method of measuring intraocular pressure is known, comprising static deformation of an eye by means of the weight of a support with annular supporting part and dynamic deformation of an eye cornea through eyelid by means of a ball freely falling from the height 120-150 mm with the weight 0.3-0.7 g and further determining of the amount of pressure by the first ball rebound (RU 2007951, Cl. A 61 B 3/16, 29.06.90).
In the above method measurement accuracy depends greatly upon individual eyelid structure and features (eyelid thickness, resilience etc.).
The square of interaction of a ball with an eyelid and an eye differs depending on resilient features of patients"" eyelids and eyes. The above method does not exclude the influence of differences in shock-absorbing features of eyelids.
Using of an annular support does not eliminate eyelid shock-absorption in places of interacting of the support with an eye through eyelid and does not provide stable reliable interaction of the device with an eye during measurement.
Tonometer-indicator is known for measuring and indication intraocular pressure, comprising a housing, a scale and an eyelid-covered cornea deformation means in the form of a ball, disposed in the housing (in a form of a tube) with transparent working part, enabled to fall free inside the housing and being retained in the upper non-working state by means of a holder, secured in the upper part of the housing, and a stop member, secured in the lower part of the housing for limiting the lower position of the ball (RU 2007951, Cl. A61B 3/16, 29.06.90).
The eyelid deformation by the annular supporting part of the tonometer does not eliminate shock-absorption of an eyelid in the setting place. Besides the rigidity of the connection of the support with an eye is not provided in this tonometer.
A device is known for measuring intraocular pressure, comprising a housing, a bush located within the housing, being adapted to reciprocate within limits and having guides and a supporting part for creating constant set load, an eyelid deformation member, located within a bushing, being adapted to fall in the guides under the influence of its own weight for creating striking load, a holder for retaining the deformation member in the initial upper non-working position, located in the upper part of the bush inside, the lower guide being the stop member for the lower position of the deformation member inside the bush, and the measuring transformer of the linear displacement of the deformation member (RU 2099000, Cl A61B 3/16, 20.12.97).
Using of a falling rod increases the accuracy of measuring IOP because of a small area of its base for eye deformation.
However the annular supporting part does not provide the rigidity of the connection of the device with the eyelid-covered eye and does not eliminate shock-absorption of an eyelid.
Thus in all the known devices deformation of an eyelid by the annular supporting portion does not eliminate the influence of the shock-absorption features of an eyelid, which decreases the accuracy of measurement of IOP.
Besides large area of the annular support does not permit to place it on small gristle section of an eyelid.
The technical result at which the proposal is aimed consists in increasing of accuracy of measurement of IOP by means of eliminating the influence of shock-absorption of an eyelid and by means of increasing the rigidity of the connection of the supporting portion with the eye because of static eyelid deformation by the support weight while measuring IOP in the gristle region.
Additionally there is provided stability of maintenance of the distance between the eyelid surface, on which dynamic deformation of an eye is realized, and the rod base in its initial position.
To achieve the technical result there is provided a method of measuring intraocular pressure through the eyelid, comprising static deformation of an eyelid by support loading with simultaneous dynamic deformation of an eyeball through an eyelid by a body freely falling relative to the support with further determining the amount of resilient deformation of the eyeball surface, wherein static deformation of an eyelid by support load is realized in its gristle region by two projections of the support, located at equal distances 7-10 mm from the axis of displacement of the freely falling body, providing a decrease of eyelid shock-absorption under the support.
Advantageously the method includes realizing additional static deformation of the eyelid section, on which dynamic deformation of an eye is realized, by subjecting to applanation of the surface of this section parallel to the base plane of the freely falling body by means of pressing the edges of this eyelid section to the eyeball, providing constant distance between its surface and the base of the freely falling body in its initial position.
Advantageously determining the amount of resilient deformation of the eyeball surface, partially covered by an eyelid, is realized from the parameters of the time function of displacement of a freely falling body.
Preferably in the course of measuring dynamic deformation of an eyeball is realized by means of a flat base with the area 1-7 mm2 of a freely falling body having the form of a rod.
To achieve the technical result there is provided a device for measuring intraocular pressure comprising a housing, a bushing located within the housing, being adapted to reciprocate within limits and having guides and a supporting part for creating constant set load, an eyeball deformation member in the form of a freely falling body, located within the bushing, being adapted to fall freely in the guides under the influence of its own weight for creating striking load, a holder for retaining the eyeball deformation member in the initial upper position, located in the upper part of the bushing inside, the lower guide being the stop member for the lower non-working position of the eyeball deformation member inside the bushing, and a measuring transformer of the linear displacement of the deformation member, the supporting part of the bushing having two projections with rounded supporting ends, located at equal distances 7-10 mm from the axis of displacement of the freely falling body.
Preferably, the projections of the supporting part of the bush are wedge-shaped, and their working surfaces facing each other have the angle of slope equal to 10-30xc2x0 to the displacement axis of the freely falling body.
Advantageously, facing each confronting working surface of the projections of the supporting part of the bushing has the height 5-10 mm, the width 4-6 mm and the radius of rounded supporting ends 2-3 mm.
Advantageously, confronting working surfaces of the projections of the supporting part of the bushing, have concave form. Preferably, the supporting part of the bushing has a member for applanation of an eyelid section surface, contacting with the freely falling body during striking loading, parallel to the base surface of the later for providing constant distance between the eyelid section surface and the base of the freely falling body in the initial position.
Advantageously, the member for applanation of an eyelid section surface, contacting with the freely falling body during striking loading, has the form of an annular projection 2-3 mm high, which working pressing base is located at the height 3-5 mm from the bases of the projections of the supporting part of the bush.
Advantageously, the supporting part of the bushing has recesses at the butt working surface between the annular and wedge-shaped projections.
Advantageously the supporting part of the bushing has channels for letting air out of the bushing during body falling.
Advantageously, the walls of the bushing outside is supporting part have channels for letting air out, connected with the bushing inside.
Preferably, the deformation member has the form of a rod with a displacement limiting member.
Advantageously, the rod displacement limiting member has the form of a cylinder, rigidly connected with the rod coaxially with it.
Advantageously, the end part of the rod contacting with an eyelid during striking loading has the length not less than 3 mm and a flat base with the area 1-7 mm2.
Advantageously, the rod holder has the form of a horizontal spring plate catch with a hole for catching the upper end of the rod and with a splay on a side surface for interaction with a pin, secured on the wall of the housing, the upper end of the rod has a stop member for interaction with the plate catch, and the pin serves as a drive of horizontal displacement of the plate catch while displacing the housing downward relative to the bushing.
Preferably, the measuring transformer of the linear displacement of the eyeball deformation member comprises a generator connected with an electromagnetic coil, secured in the bushing between the guides, and a data processing device, and the rod displacement limiting means serves as the core of the electromagnetic coil.
Advantageously, the device includes a means for fixing the bushing in the initial position in the housing, including sprung button, pressing part of which is located in a hole of the housing wall enabled to interact with the outer surface of the bushing.
Using of the supporting portion with projections with small base area permits the increase of loading of the support on the eyelid in their setting places, providing pressing of the eyelid to eliminate its shock-absorption, and to provide rigid connection of the supporting portion of the device with the eye during measurement.
Besides placing the support projections on the eyelid in the gristle region eliminates eye deformation under the projections.